The present invention relates to magnetic recording and reproducing apparatus which record/reproduce signals such as speech signals to/from a traveling magnetic tape, and more particularly to a mechanism which controls the travel of a tape such as a pinch roller changing mechanism for changing a pinch roller pressed against a capstan to thereby change the direction of tape travel and a fast feed/rewinding mechanism which performs the fast feeding/rewinding operations of a tape.
Recently, tape players of the type which drive a magnetic tape in a forward and a reverse direction have widely sold. A player of this type usually has five modes: stop, play, fast feed (FF), rewinding (REW), and program change. At preset, in order to improve the operability, so-called full-logic compatible type tape players in which a microcomputer incorporated into the player controls those operational modes have been developed and put to practical use.
Conventionally, in such a tape player, a mechanism is provided which controls the position of the head for each mode. In this mechanism, the head is mounted on a plate called a head plate, which is driven, for example, by a motor such that the head plate is held at a position where the head contacts the tape or at a position where the tape moves away from the tape in accordance with the selected mode.
In order to change the direction of tape travel, a mechanism which changes between a take-up side and a supply side and a pinch roller changing mechanism which changes the pitch roller pressed against the capstan are provided. One example of the pinch roller changing mechanism is the technique disclosed in a published unexamined Japanese patent application Sho. 58-57820 (1983). In this technique, an intermittent gear is provided as means which does not interfere with a position control structure for the head plate. The gear has a cutout with successive teeth formed around its inner periphery except at two spaced points and a cam which performs a locking operation at each half rotation. The intermittent gear is combined with a drive gear which is normally rotated in connection with a motor. A solenoid involving a plunger forcedly changes the pinch roller pressed against the capstan when tape travel is changed.
As a fast feed/rewinding mechanism used in a tape player of the type which has modes such as are mentioned above, a mechanism has been proposed in which a microcomputer gives a FF operation command or a REW operation command in accordance with the operation of an FF/REW switch to thereby perform an FF or a REW operation. Generally, this FF/REW mechanism is provided with a drawing solenoid which operates in accordance with a command from the microcomputer. In the FF or REW operation, the drawing solenoid performs a drawing operation such that an FF/REW gear is pressed against a flywheel gear and a reel base to perform the FF or REW operation.
The above-mentioned conventional pinch roller changing mechanism and FF/REW mechanism have the following drawbacks. In the pinch roller changing mechanism and the FF/REW mechanism, means such as a solenoid and an intermittent gear are generally used in order to change the pinch roller and the FF/REW gear when the mode of tape travel is changed. In this case, the solenoid provides an electromagnetic coercive force enough to hold members in a given state with small power consumption, but does not provide an electromagnetic coercive force large enough to drive the members forcedly, so that many members are required which include a spring and other members to provide such a large drive force. Many members are required to be provided around the intermittent gear in order to convert the drive force to an operation in a given direction. As the number of parts increases, the number of steps of assembly is large, so that assembling is complicated and, as a result, the assembly accuracy is reduced and the reliability of the tape travel control mechanism is reduced. The use of many parts and the complication of the mechanism would reduce the degree of freedom of design in a tape player. In addition to such complication of the structure, since the sizes of the solenoid and the intermittent gear themselves are large, large spaces for installation are required. As a result, this is a large hindrance to reduction of the size and weight which are required for the tape player. In addition, the use of many members and the complication of the mechanism increases the total cost of the members.
Therefore, it is required to provide an excellent tape travel control mechanism which uses a small number of parts assembled and is easy to assemble, excellent in the reliability of the mechanism and the degree of freedom of design, contributory to reduction in the size and weight of the overall tape player, and inexpensive.